1. Field of the Invention
The present invention relates to a stator arrangement of an alternator driven by an internal combustion engine for a vehicle such as a passenger car, a truck, or a boat.
2. Description of Related Arts
In a manufacturing process of the stator of an alternator for a vehicle, a plurality of hair-pin like conductor segments (having a turn portion) are inserted into corresponding slots and connected one another instead of winding a continuous wire. Because the above stator needs many joint potions, an automatic wire connection machine is indispensable to reduce the production cost.
Such a stator of an alternator for a vehicle having conductor segments is disclosed in PTC Patent Application 92/06527. The joint portions of a plurality of conductor segments are disposed annularly on one axial end of the stator core, and those are soldered or welded automatically. It is also disclosed that four segments are disposed in a slot, and that segments specific to the joint portions corresponding to the turn-over portions and in-between portions are formed beforehand.
PTC Patent Application 92/06527 discloses as shown in FIG. 21 of this application, a wave winding formed of segments two conductor members of which are respectively disposed in an outer layer and an inner layer in a slot. FIG. 20 shows a winding diagram for one-phase winding. The numerals disposed in a line at the center thereof indicate the slot number. A solid line indicates a conductor member inserted in position A of the slot shown in FIG. 21, a one-dot-chain line indicates a member in position B, a two-dot-chain line indicates a member in position C, and a broken line indicates a member same in position D.
A plurality of the conductor segments includes some base segments 105 having the same length and the same shape. Base segment 105 has two straight conductor members respectively disposed in slots separate at one-pole pitch from each other. One winding is formed from a plurality of the base segments disposed and connected in a regular pattern.
However, such a winding has four conductor members in a slots, thereby forming four wave windings wound around the stator core. In order to connect four windings in series, specific segments different from base segments have to be used. The specific segments of this case include specific segment 100 for connecting the first and second turn windings, specific segment 101 for connecting second and third turn windings and specific segment 102 for connecting the third and fourth turn windings 102.
In order to have two output terminals X1, X2, two specific segments 103, 104 are used.
As a result, in order to form one-phase winding, five different specific segments are necessary. Output terminals X1, X2 are disposed one-pole-pitch separate from each other to avoid interference with the base segments of Y-phase and Z-phase windings because each of output terminals X1, X2 is one of the conductor members inserted in the outer layer in the slot.
Thus, the above conventional winding needs five specific segments to form a one phase winding. In other words, a four-turn winding is formed around the stator core by connecting conductor segments having four conductor members inserted in the same slot in the stator disclosed in PCT Patent Application 92/06527.
The step of inserting the segments in the slots and the step of connecting the ends of the segments for forming one annular winding are the same with all the segments. Another one annular winding is formed in the same slots as the above slots. Other two one annular windings are formed in the slots which are three-slot pitch shifted from the above slots for the first two annular windings. Thus, four annular windings are formed.
In order to form a single four-turn winding by connecting the four annular windings, it is necessary to cut each of annular windings at a portion (four portions in total) and connect the windings with one another at the cut-portions. Therefore, five specific segments--three specific segments for connecting other three annular windings and two specific segments for output terminals--are necessary.
The five specific segments can not be put together at a coil end in a one-pole pitch, because the four annular windings are formed into two groups shifted a three-slot pitch from each other and are not stacked in the radial direction at the coil ends.
If two conductor members (a half of the former number) are inserted in one slot, it is possible to put the specific segments on a coil end in one slot-pitch together. However, reduction in the number of turns can not provides the output voltage of the alternator at a low seed.
FIG. 20 shows conductor members extending from the inner layer are connected to conductor members extending from the outer layer at joint portions 106. Therefore, the conductor members extending from both inner and outer layers of the respective slots are inclined in the same direction, and do not interfere with one another.
In the stator winding disclosed in PTC Patent Application 92/06527, joint portions 106 are disposed annularly on an end of the stator core. Therefore, if the stator is small, intervals between the joint portions become too small for the connection.
Thus, increase in the number of specific segments decrease in the interval between the joint portions make the manufacturing steps of the stator more difficult and the production cost higher.
PTC Patent Application 92/06527 teaches that lap (or loop) windings of the stator winding can be formed from the segments. However, there is not detailed description about it.
The object of the present invention is to provide a stator having a substantial number of conductor members in a slot with a small number of annular windings.